cuVHS

GPU-accelerated VHS RF signal decoder. Takes raw RF captures (.u8 files from an RF capture device) and produces timebase-corrected (.tbc) output compatible with ld-tools for video export.

Status: Early development. NTSC only for now — support for additional video standards is planned.

What it does

cuVHS replaces the decode step of vhs-decode, running the full signal processing pipeline on the GPU:

• FM demodulation
• Sync pulse detection
• Line location + hsync refinement
• TBC luma resampling
• Chroma decode (VHS color-under)
• Dropout detection

The output is a pair of .tbc files (luma + chroma) plus a .tbc.json metadata file. To get viewable video, you still need tbc-video-export and ld-tools from the vhs-decode ecosystem.

Performance

~85 FPS on an RTX 3090.

Requirements

• NVIDIA GPU (compute capability 6.0+)
• CUDA toolkit
• CMake 3.25+
• cuFFT (included with CUDA toolkit)

Build

mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make -j$(nproc)

Usage

./build/cuvhs -f <sample_rate_mhz> --overwrite <input.u8> <output_base>

Example with a 28 MHz capture:

./build/cuvhs -f 28 --overwrite tape.u8 tape_output

This produces tape_output.tbc, tape_output_chroma.tbc, and tape_output.tbc.json.

Viewing output

Install tbc-video-export and ld-tools, then:

tbc-video-export tape_output tape_output.mkv

License

BSD 3-Clause. See LICENSE.

If you use cuVHS in published work, please cite this repository. See CITATION.cff.